Conventionally, in the production of semiconductor devices, fine processing by lithography using a photoresist composition has been performed. The fine processing is a processing method including: forming a thin film of a photoresist composition on a substrate to be processed such as a silicon wafer; irradiating the resultant thin film with an active ray such as an ultraviolet ray through a mask pattern in which a pattern of a semiconductor device is depicted for development; and etching the substrate to be processed such as a silicon wafer using the resultant photoresist pattern as a protecting film. Recently, however, the high integration of semiconductor devices has progressed and the adopted active ray tends to have a shorter wavelength, such as an ArF excimer laser (193 nm) replacing a KrF excimer laser (248 nm). Following such a tendency, the influence of diffused reflection of an active ray on a substrate or a standing wave has become a large problem. To address this, what has been widely studied is the use of an anti-reflective coating (Bottom Anti-Reflective Coating, BARC) between the photoresist and the substrate to be processed.
Progress in refinement of the resist pattern will cause a problem of the resolution or collapse of a resist pattern after development; therefore, thinning of the resist will be required. In this sense, it is difficult to secure a resist pattern film thickness sufficient for processing the substrate, which requires a process for imparting a function as a mask for processing the substrate not only to the resist pattern, but also to the resist underlayer film provided between the resist and the semiconductor substrate to be processed. As a resist underlayer film for such a process, there have started to be required a resist underlayer film for lithography having a selection ratio of a dry etching rate close to that of the resist, a resist underlayer film for lithography having a selection ratio of a dry etching rate smaller than that of the resist, and a resist underlayer film for lithography having a selection ratio of a dry etching rate smaller than that of the semiconductor substrate, as a resist underlayer film, unlike a conventional resist underlayer film having high etching rate property (high etching rate).
In addition, a heat resistant resist underlayer film having a fluorene structure is disclosed (Patent Document 1).